A 55-year-old man presents with nephrotic range proteinuria, macroglossia, and hepatomegaly. Renal biopsy stained with Congo red shows amorphous eosinophilic deposits in glomeruli and vessel walls. Serum free light chains show an elevated lambda level with kappa:lambda ratio of 0.2. The underlying disorder is:

• A AA (secondary reactive) amyloidosis
• B Light chain deposition disease
• C ATTR hereditary transthyretin amyloidosis
• D AL amyloidosis from a plasma cell dyscrasia ✓

Explanation

AL amyloidosis arises when a clone of plasma cells produces excess monoclonal light chains, usually lambda, that deposit as beta-pleated sheets in tissues such as kidney, heart, tongue, and liver. Congo red staining gives apple-green birefringence under polarized light. AA amyloidosis follows chronic inflammation and involves serum amyloid A, ATTR involves transthyretin, and light chain deposition disease produces non-fibrillar granular deposits that stain weakly with Congo red.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.